Bleaching reducing

Reduced viscosity Reducing bleaches Reducing sugars Reduction... 

There are two types of bleachiag oxidative and reductive. Oxidative bleaching cleaves carbon—carbon double bonds thus destroyiag chromophores. Reductive bleaching reduces carbon—carbon double bonds to single bonds. The loss of extended conjugation ia the chromophore leads to loss of color. 

Numerous workers126-132 have combined PB with the conducting polymer polyaniline in complementary ECDs that exhibit deep blue-to-light green electrochromism. Electrochromic compatibility is obtained by combining the colored oxidized state of the polymer1 with the blue PB, and the bleached reduced state of the polymer with PG (Equation (17)) ... 

Prebleached wool becomes somewhat yellow on dyeing. To obtain clear pastel shades bleach and dye are used preferably in the same bath. Mildly bleaching reducing agents (especially stabilized bisulfite or hydroxylamine salts) can be employed because they do not affect the dyes used. 

More recently, Schuster [25] has demonstrated that cyanine dyes, i.e., cyanine borates or cyanine dye-borate mixtures, provide visible light activated initiation of free radical polymerization [26]. The photoexcited cyanine dye oxidizes alkyltriphenylborates by PET to produce the bleached reduced cyanine along with an alkyl radical. The alkyl radical can then initiate free radical polymerization [27], This visible light activated PET bond cleavage is of considerable importance in photoimaging and photocuring [28]. 

Bleaching. The refined oils are usually dark in color owing to the presence of some pigmented materials such as chlorophyll or carotenoids and minor impurities like residual phosphatides, soaps, metals, and oxi-datin products. Bleaching reduces the color by absorbing these colorants on bleaching earth (bentonite clays), or activated charcoal, or both. In addition to decolorization, bleaching clay also absorbs suspended matter and other minor impurities. 

Reversible chemical reduction of the red oxidized crystals yields the bleached reduced species without damage of the crystalline particles, thus indicating that the conformational change which accompanies the... 

A second important aspect of electrochromism is the temporal response under alternating potentials ( 0.55 V). The DG showed sharp and distinct transitions between the colored/oxidized and bleached/reduced state across the entire visible spectrum (Fig. 6.10b). This time-resolved switching behavior was analyzed in more detail at A = 630 nm (Fig. 6.10c). The DG device showed short characteristic response times of 53 ms for the bleaching step and 63 ms for the reverse process, determined by fitting exponential functions to the switching curves. These short response times which are close to video rate (24 frames per second) are enabled by the short ion diffusion distance through the only >= 5 nm thick NiO nanotube wall. 

The metal traces present in oils cause generally no problems concerning the health, but as prooxidative components they influence the oil quality unfavourably. Alkali refining and bleaching reduce the metal content. 

During the manufacture of edible oils bleaching reduces the chlorophyll pigment content to the highest extent, other stages of refining have a small effect. 

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